Opacifier for enamels



Patented Dec. 2, 1930 s or DELAWARE.

@ imparttothe enamel a desirable white color.

A further object is to provide such an enamel 1 particularly suited for dry process [application on cast metasimh ascast' iron orfisteel." My invention consists 'i'n'providmg enamel 1 i0- ixtures containing sodium" antimoiiategand oxide as 'opacifierf Th'ave'tried various imi'xtur'es of sodium antimonat'e and'tin oxide" in a number of varied formulae; butjlhave i found that the'best results are secured if the 15 two constituents arepresent'inalmore 01" less restrictedratio to eaf hi other; a I have found'that the sodium antimonate-tin oxide ratios should be approximately 3; 1;; If this ratio is altered in either direction the enamel inwhich it is. used does not have the desired opacity andphysical'properties; {I- have found that in the enamels of-my invention this 3 :-1- mixture can be utilized in amounts su flic'ient to give desiredbpaeity andcolor,

52;; and stillnot rendertheen'amelbrittle or increase its tendency to -chip off i. e.-the-proper cubical expansion of the enamel necessary to secure the proper adherence to the :iron or steel under temperature changes can be 4 Ihave further discovered thatto secure the proper. adherence} and other desirable, qualities in' such enamels several components J obtained evenwith "high-amounts of" :55 must be used in more or less defin'itepropor tions: vThe following examples gives these 7 components inthe preferred proportionsand the variable allowances whichfl'maybeumade inthe componentstojsecure small variations 5&9 in the expansion coefficient to conform tothe metal; The individual coeflicients ofexpansion of the components are given inithe literature so" that havingthe basic formula given here below the desired composition canj-b'e madeup to fit any particular cast metal.-- Y 7 THQMAS METUCHEN; Wh Iii EY;AssIeNon-nY-mmsNE- ASSIGN V A i c- MENTS TOHTHE. GOMIEA GORPORATI p v V 2 e .7 orimm3 Foit'nNAMEns I Maeg n meaj ns iz,192s. seriiznb eiases. 1 v

j Dry process cast M'OTL enamel i f1 Pie: 7 ferred vvi gfi frit for allowi mula anszes v Feldspar (parts by weight)" 37. 0' 35 to 39 Borax (parts by weight) 13.0 11 to 14 Soda mtre (parts by weight)- 2, 5 H 2 to: 3 Soda ash gparts by weight) 7.0 5 to 8- Cryol teqiarts'by weight) 4.0 i 3 to -6 Fluorspar (parts by weighty 6.0 5 to 7 O Whiting (parts by weight) 3.0 1' to 4 Red lead (parts by weight) 15.0 10 to 15 Zinc oxide (parts by weight) 4. 5 i 3 to 7 A nt mony-t nopaeifier (parts by i 8.0 4 to 12 v lef'an d in the appended. cla ms myppa'ci er "is re'ferred to as antimony-tin opaci'fier',and the amount required denotes the amount of 3:1 miXture'usedf V The materials ofthis formula:

a m xed byi an l 1; me a llys and then' fused the melt iSd iOPPQdinto water to cool and shatter after: which it is placed in the ba l mi land ground together to a fineness best suitedgfjor the particular methodof application to be used ;--this erallybetween' about B Q ZO mesh. a v

In usingthisenamelon cast iron-a slnish'or bindingrcoat is first applied to; the article. Th s undercoat may be any of the coating Compositions suit edifor the articles. Such a: slush coat for cast metal is f orined'by fusing together feldspar, flint, .borax, red lead and saltpeter to form a frit in grinding this with 7 water; clay and further amounts offeldspar and flint; This mixture is applied to the castingand then firedat a temperature of about 875 0.; the casting is then withdrawn from the furnace and the powdered enamel dusted on the hot casting after which the casting is again fired, Several applications of the enamel can thusv be made depending on the thickness of enamel desired; I noted above the maturing temperature of this enamel is about; 850 O. perioldfof about 5 I'ninutes at this temperature isusually satisfactory.

6 5 Will be gen- 7 When thus burned the above enamel has the following empirical formula when calculated on a basis wherein the sum of the sodium, potassium, calcium, lead and tin oxides is equal to one.

Mols.

Na O 0.407 K 0 0.068 CaO 0.252 A1 0 0.171 B203 Sb O l 0.030 SiO 0. 970 S110 0.030 F 0.174 PbO 0.149 ZnO 0.123

The coefficient of expansion obtained with the preferred formula is 365.4 X

The variable compositions allowable in this flux will result in fluxes having a variable fomposition by weight approximately as folows:

Na O 9 K 0 2 5to 3 -CaO 4 to 8 A1 :3 7 to 9 13 0 4 to 5 Sb O 2 to 6 SiO 24 to 28 SnO 1' to 3 2-; 2 t0 4: P100 10 to ZnO 3 to 7- In the above formulae it will be noted that the opacifier allowances cover a wide range; the actual amount to be used depends on the opacity desired.

' While I have explained the opacifier as being a definite mixture of the two materials,

I have found that it is not necessary to actu-.

ally mix o'r'grind the antimonate and tin oxide together before adding them to the enamel. I have found that the opacifying results are equally well, secured if, for example, the two were. mixed prior to the addition of the enamel, or whether they were added separately,the only requirement being that the ratio approximately be maintained. Regardless of 110w the two materials are added any deviation from the ratio 3:1 is immediately apparent by a change in the appearance and properties of the enamel. be seen from the above I do not wish to be limited to the manner of adding my opacifying mixtures to the enamel. The sodium antimonate of my antimony tin opacifier may be supplied by pure sodium antimonate as such, or I may use the material commonly known in the art as leukonin which consists chiefly of sodium antimonate, and therefore in the appended claims, I wish it understood that sodium antimonate is intended to cover such It can mixtures, and the term antimony tin opacifier is intended to cover such materials as leukonin in combination with tin oxide as well as the pure material.

Formulae suited for sheet steel and wet process cast iron enameling embodying my invention are given in my copending applications, Serial No. 246,397 and Serial No. 246,399 respectively, filed of even date herewith.

Claims: 1. An enamel composition comprising:

- Parts by weight Feldspar to' 39 Borax 11 to 14 Soda nitre 2 to 3 Soda ash 5 to 8 Cryolite 3 to 6 -Fluorspar 5 to 7 W'hiting l 1 to 4 Red lead l 10 to 15 Zinc oxide -1 3 to 7- Antimony-tin opacifier (3:1) 4 to 12 2. An enamel composition comprising:

i Parts by v a 7 weight Feldspar l 37.0 Borax 1 13.0 Soda nitre 1 2.5 Soda ash 7.0 Gryolite 4.0 Fluorspar v 6.0 Whiting 3.0 Red lead' l 15.0 Zinc oxide i 4.5 Antimony-tin opacifier (3: 1) 8.0

3. A fired enamel having the following empirical formula:

4. A fired enamel having a composition by weight approximately as follows:

to 12.5 K 0 2.5 to 3 C210 4 to 8 A1 0 7 to 9 13 0 4 to 5 S10 0 2 to 6 SiO 24 to 28 SnO 1 to 3 F 2 to, 4 PhD 10 to 15 ZnO 3 to 7 wherein sodi ul n antimon ate and tin oxide areutlhzed 1n the requlslte amount m the preparation of the compositionl for firing and in the ratio to each other of 3 to 1 v Signed at Perth Amboy, in thecounty of Middlesex and State of New Jersey, this tenth day-ofJanuary, A, 71928 THOMAS H. K OWN. 

